Material anb



R P LUTZ Aug. 22, 1944.

COMPOSITE INSULATlNG MATERIAL AND METHOD OF MAKING SAME Original FiledOct. 31. 1956 FIG. 2

lNVWTOR R. FLU rz 6% 4 Arrow/m Reluued Aug; 22, r

UNITED? 1s comosrrs;'rssmrrsomrmm;

METHOD OF MAmNG-"sAMu-q Western Electric 'Conih'anm- Incorporated; New?York, N. Y., a' corpora 2,112,445; dated s'eptember Serial No; 108,610,Octo tion tor-reissue January-28,1943, Serial-fr w materials andcompositions suitable -ior-impregnating such materials and-to methods ofimpre hating fibrous materials, and is: a continuation in 2 part of mycopending applications,SerialiNoI;

713,866, filed March 3, 193 4, and Serial No. 752,467, filed November10,1934.

Objects of the invention are to provide materials having goodnon-hygroscopic andinsulat z,

ing properties for use in electrical apparatus and to provide improvedcompositions] and -method'sior impregnating fibrous matensm; 1

In accordance with one embodiment oi the 111- vention, a fibrousmaterial suitable for iillingor" encasing electrical coils isimpregnated with "VinsoP or a solution or Vinsol and cellulose Iderivatives to insulate the coil--and '-prevent corroslon oi theelectrical conductors." Other oblects and advantages the descriptionproceeds.

A complete understanding oithe'inventlon may will appear as 1 be-ha'd byreference to the following description taken in conjunction with theaccompanying drawing, in which 7 Fig. 1 is a perspective view, partlyinsection, of a coil embodyin the invention;

Fig. 2 is a modified form of coil embodyin the invention; and

Fig. 3 is a fragmentary detail view of the covering for the coil shownin Fig. 2.

Referring more particularly to Fig. 1, the coil may be provided with arectangular fibrous material or the core may be made of a phenolcondensation product, of cellulose acetate, or of a phenol condensationproduct laced with cellulose acetate. wound in layers on the core andeach layer is separated by a fibrous sheet or paper, c loth, or the likeand a similar sheetls wrapped aroundthe outer layer of wire. Thewire maybe bare, it suitably spaced, but preferably comprises enameled wire orwire having a fibrous insulamaterial comprising a gasoline-insolublepine be immersed in" core 5 of Vinsol" by the HerculessPowcle'r Com'pany. "Vinsol" is a hard dark-colored resinous wood resin, produced byextracting resinous wood a with a coal tar hydrocarbon by evaporation.exv tracting the v U I v I carbon, removing the solventand recoveringthe gasoline-insoluble resin as I No. 2,193,026, issued March 12,1940,to Lucius-C. Hall.

residue with a petroleum hydro? described in Patent- The convolutlons 01wire are v of cellulose acetate maybe dissolved in 400 parts 1 ofacetone 1 and the mat'erials then -mixed" to: gether, or Vinsol mayfrbeadded directly to' a" plastieor less brittlematerial*-for manyiisesnweight-20f acetone:

as uneconomicaLi thoroughly impregnatesthe'flbrous mate'rial mthe -mwdein this manner have-been iound to have 'a 'v'e'ry iow 'hyz ioscopicltyand *high corrosion resistance and' due to theand-lowtdielectric "coneserous-material; the" material is excellently suitedtor insulating'coilm For some purposes a; coil mad-easdescribedabove may be dippedin'a solution' oicellulose acetateand Vinsol to provide a' 'moreelastic-coverin'g for the outside oi the coil or it maybe dipped' insuch. a solution without previously ciippmg it"in a solution of' theVinsol, It has been'w found that a; solution of cellulose acetates in"acetone by" itselfhas poor impregnatingproperties-since it, in efcoil.'lests made'kon coils high insulation resistance stant'oi theimpregnated w cellulose acetate into the'flber. The addition-oi thecellulose acetateto the Vinsol raises themelt ing point'oi thecomposltion'*over-- that oi the Vinsol alone and thecomposltion'containlng the two ingredients is, 'thereiore,more'suitable-ior coils which are operated at high temperatures.

In preparing a solutionbi cellulose'acetate and Vinsol, parts '0!.vinsol 'mliy' be first dissolved in about '75 parts 'ot'aceto'neand 100parts 1 i solutionof 1 cellulose acetate in acetone. 1

Preferably, the cellulose acetate may confstltute" an amountequal'totheamountcf Vinsol, 'al

though these materials are-soluble in all propor-* Vlnsol is. used, theproperty'oi causlngthe' celthe product becomes brittle and tendsto'llakeu- Vinsol alone is qult'eibrlttle an'dtnds to be-" come powderywhendry; igl-lowiever, a' solution oi this materl'alwith a celluloseester makes-a more This composition is thermoplastic" and :canbe formedlnto'sheets or articles in a" mold under as 'heatandpressure. Thematerial can be prepared lose acetate in acetone to the posite sheet.

for molding lay dissolving the ingredients in acetone', as previouslydescribed, evaporating. the

solvent, and pulverizing the residue into particles of suitable size. Inpreparing this material, a

relatively viscoussolution can be used to reducethe quantity ofacetonerequired for the impregnating solution. It is also feasible to reducethis solution to sheets ormolding slugs by evaporating the solvent fromsolution contained in forms of the proper contour. For otherapplications, the

' cellulose ester and Vlnsol may be mixed'in powdered form, placed in amold, and subjected to heat and pressure to consolidate the material-andoils without impaira fibrous material impregnated with cellulose acetateand with a resin which is the residue formed by extracting pine woodwith a coal tar hydrocarbon, evaporating the coal tar hydrocarbon andother volatile constituents from the extract to produce a solid residue;extracting rosin from said residue with a light petroleum hydrocarbon,and separating the rosin extract from the remaining residue, which issubstantially insoluble in light petroleum hydrocarhens and recoveringthe remaining residue.

3. A method of making an insulating material which comprisesimpregnating fibrous material with cellulose' acetate and analcohol-soluble resin which is the residue produced by steaming pinewood chips to remove volatile substances therefrom, extracting thesteamed wood chips with a coal tar hydrocarbon, evaporating the coalFig. 2 illustrates a coil having a core 6 comprised of cellulose acetateor a phenol fiber condensation product faced with cellulose acetate.

The coil iswound on the core in layers and the layers are separated fromeach other by sheets of fibrous material. After the coil has been wound,it is impregnated with a solution of Vinsol or the coil maybeimpregnated witha solution of, Vinsol and cellulose acetate. After thecoil is impregnated, heads I of cellulose acetate or phenol fiber facedwith cellulose acetate are adhered to the core by applying a solution ofcelluends of. the core and pressing the head against the core until thesolvent dries. If it is desired to have a hermetically sealed coil, anouter sheet I may be applied to the coil. This sheet is made byimpregnating a fibrous sheet 9 with Vinsol or a solution of Vinsol andcellulose acetate and then applying a sheet ll of cellulose acetate toeach face of the impregnated sheet 9. The cellulose acetate sheets maybe adheredto the impregnated sheet 9 by subjecting the composite sheet.plasticize the cellulose to heat and pressure to acetate and mold itintegral with the impreg nated fibrous sheet. This procedure insuresthorough impregnation of the fibrous material so that when the sheet israw or unimpregnated fiber. In covering a coil, as shown in Fig. 2, apiece of this composite sheet is cut so that its edges will overlap whenwound about the coil and the ends will abut the heads 1. A solution ofcellulose acetate inacetone may then be applied between the overlappingedges and along the ends where they abut the heads to completely andhermetically sealthe coil.

- While the invention has been described in connection with particularembodiments thereof, it

will be understood that many changes and modifications may be madewithout departing from the spirit and scopeof the invention.

What is claimed is:

1.. An insulating material comprising a fibrous sheet impregnated with acomposition of cellulose acetate and an alcohol-soluble resin having amethoxy content of about 3% to about 6% which is extracted from pinewood hydrocarbon and from which resin has been extracted with a lightpetroleum hydrocarbon,

said fibrous sheet having a sheet tate adhered to one face thereof ofcellulose aceto form a com- 2. A method of making an insulating materialwhich comprises adhering a sheet of cellulose acetate to one face oi. acomposition comprising with a coal tar insoluble components of theresidue, extracting rosin from said residue with a lightpetroleumhydrocarbon, and separating the extract from the light petroleumhydrocarbonoriginal extraction of pine wood, applyinga sheet ofcelluloseacetate to one face of the thus impregnated fibrous material, andadhering the cellulose acetate sheet to the impregnated fibrousmaterialwith heat and pressure.

4. a method of making an insulating material which comprisesimpregnating a fibrous material with a mixture of a cellulose derivativeand. a

resin which is soluble in alcohol and substantially insoluble in lightpetroleum hydrocarbons and which is produced by extracting pine woodwith a coal tar hydrocarbon to produce an extract containing coal tarhydrocarbons, volatile materialasuch as turpentine, and normally solidresinous materials, evaporating the coal tar hydrocarbon and volatileportions. of the extract to produce a solid residue, extracting rosinfrom said residue with a light petroleum hydrocarbon, separating thesaid rosin extract fromthe ,then remaining insoluble residue andrecovering the said insoluble residue which has the aforesaid anddesired. characteristics, and applying a sheet of cellulose derivativeto one face of the impregnated fibrous material, and adhering the sheetfibrous material with heat and pressure.

' 5. A method of making, an insulating material which comprisesimpregnating a fibrous material with. a mixture of cellulose acetateanda resin which is substantially insoluble in light petroleumhydrocarbons and which has a 'methoxy content of between about 3% toabout 6%, which resin is produced by extracting pine wood with a coaltar hydrocarbon to produce an extract containing coal tar hydrocarbon,other volatile substances such as turpentine and pine oil, rosin, and asolid residue, removing the coal tar hydrocarbon and other volatilematerials to produce a mixture of rosin and said solid residue,extracting rosin from said mixture with a light petroleum hydrocarbon,and separating said rosin extract from said solid residue which has theaforesaid and desired characteristics, applying a sheet of celluloseacetate to one face of the impregnated fibrous material, and adheringthev cellulose acetate sheet to the fibrous material with heat andpressure.

carbon, and separating the rosin extract from. the remaining residuewhich is substantially insoluble in light petroleum hydrocarbons andre'- separating said rosin extract from said solid residue which has theaforesaid and desired charcovering the remaining residue which has theaforesaid and desired characteristics, assembling a sheet of celluloseacetate to one face of the impregnated material, and applying heat andpressure to the assembly to form the cellulose acetate sheet andimpregnated material into a composite sheet.

'7. A method of making an insulating material which comprisesimpregnating a fibrous material with cellulose acetate and a resinproduced by extracting pine wood with a coal tar hydrocar- I bon toproduce an extract containing coal tar hydrocarbon, other volatilesubstances such as turpentine and pine oil, rosin, and a solid residue,removing the coal tar hydrocarbon and other volatile materials toproduce a mixture of rosin and said solid residue, extracting resin fromsaid mixture with a light petroleum hydrocarbon, and

acteristics, assembling a sheet of cellulose acetate to one face of theimpregnated material, and applying heat and pressure to'the assembly toform the cellulose acetate and impregnated material into a compositesheet.

8. An insulating material comprising a sheet of cellulose acetate and animpregnated sheet adhered to one face of the cellulose acetate sheet toform a composite sheet, said impregnated sheet comprising a fibrous massimpregnated with a cellulose derivative and a resin characterized byfreedom from wood rosin, solubility in alcohol, substantial insolubilityin gasoline, a methoxy content of about 3% to about 6%, an acid numberof about 100, a naphtha insolubility of about 98%, and a melting pointof about 125 C., which resin is produced by extracting pine wood with acoal tar hydrocarbon, evaporating the coal tar hydrocarbon and othervolatile constituents of the extract from the extract to produce'a solidresidue, extracting rosin from said residue with a, light petroleumhydrocarbon, and separating the rosin extract from the remaining residuewhich is substantially insoluble in light petroleum hydrocarbons andrecovering the remaining residue which has the aforesaid and desiredcharacteristics. RAYMOND P, LUTZ.

Re-issue No. 22,552.

Augus t 22, 191414,.

RAYMOND P. LUTZ.

It is hereby certified that error appears in the printed specificationof the above number-ed patent requiring correction as follows: Page 1,first column, line 52,after 'carbon," strike out the words "removing thesolvent" and insert the same after "hydrocarbon" in line 50, same pageand column; and that the said Letters Patent should be read with thiscorrection therein that the same may conform to the record of the casein the Patent Office.

('Seal) Leslie Frazer Acting Commissioner of Patents.

carbon, and separating the rosin extract from. the remaining residuewhich is substantially insoluble in light petroleum hydrocarbons andre'- separating said rosin extract from said solid residue which has theaforesaid and desired charcovering the remaining residue which has theaforesaid and desired characteristics, assembling a sheet of celluloseacetate to one face of the impregnated material, and applying heat andpressure to the assembly to form the cellulose acetate sheet andimpregnated material into a composite sheet.

'7. A method of making an insulating material which comprisesimpregnating a fibrous material with cellulose acetate and a resinproduced by extracting pine wood with a coal tar hydrocar- I bon toproduce an extract containing coal tar hydrocarbon, other volatilesubstances such as turpentine and pine oil, rosin, and a solid residue,removing the coal tar hydrocarbon and other volatile materials toproduce a mixture of rosin and said solid residue, extracting resin fromsaid mixture with a light petroleum hydrocarbon, and

acteristics, assembling a sheet of cellulose acetate to one face of theimpregnated material, and applying heat and pressure to'the assembly toform the cellulose acetate and impregnated material into a compositesheet.

8. An insulating material comprising a sheet of cellulose acetate and animpregnated sheet adhered to one face of the cellulose acetate sheet toform a composite sheet, said impregnated sheet comprising a fibrous massimpregnated with a cellulose derivative and a resin characterized byfreedom from wood rosin, solubility in alcohol, substantial insolubilityin gasoline, a methoxy content of about 3% to about 6%, an acid numberof about 100, a naphtha insolubility of about 98%, and a melting pointof about 125 C., which resin is produced by extracting pine wood with acoal tar hydrocarbon, evaporating the coal tar hydrocarbon and othervolatile constituents of the extract from the extract to produce'a solidresidue, extracting rosin from said residue with a, light petroleumhydrocarbon, and separating the rosin extract from the remaining residuewhich is substantially insoluble in light petroleum hydrocarbons andrecovering the remaining residue which has the aforesaid and desiredcharacteristics. RAYMOND P, LUTZ.

Re-issue No. 22,552.

Augus t 22, 191414,.

RAYMOND P. LUTZ.

It is hereby certified that error appears in the printed specificationof the above number-ed patent requiring correction as follows: Page 1,first column, line 52,after 'carbon," strike out the words "removing thesolvent" and insert the same after "hydrocarbon" in line 50, same pageand column; and that the said Letters Patent should be read with thiscorrection therein that the same may conform to the record of the casein the Patent Office.

('Seal) Leslie Frazer Acting Commissioner of Patents.

